Drugs now in common use often require formulation compromises in order to prepare the marketed product. Thus, many parenteral compositions must be prepared using the salt of the parent compound and an excessive pH.
The instability of many useful drugs and other useful medical compositions poses other formulation problems. At present, emulsions, microemulsions and liposomes constitute the principal approaches to these problems. While such dosage forms are an advance over older forms, they are often associated with erratic bioavailability and instability of their own.
The herein disclosed invention comprises a method to prepare compositions and compositions which deliver medically useful compositions effectively. The method is based upon the use of a non-toxic aqueous coacervate; said method produces stable microemulsions comprised of particles in which one or more pharmaceutical components have been incorporated. Through the process of this invention particles are enveloped by a coacervate-based film. The compositions of this invention may be administered orally, parenterally or by tissue absorption, as required.
The disclosed method enables the preparation of particles of any desired size and any degree of particle surface film hardness, any number of coacervate-derived films of any desired thickness, or any combination of particle sizes and surface hardnesses. In preferred compositions prepared by the disclosed invention, the particle size is about 1 micron or less. The pharmaceutical component(s) may be any water soluble or water insoluble medically useful composition or combinations of such compositions.
The inventor has previously disclosed compositions based on a coacervate system using albumin and lecithin as principal components of the system. However, by polymerizing one or both of these components, the inventor has not only simplified the method but unexpectedly produced a preparation with vastly improved encapsulating capability. Details of this improvement are presented in the Experiments Section.